Fluid-pressure-controlling apparatus



FLUID PRESSURE CONTROLLING M5 AAAAAA S.

L. A. LANG.

FLUID PRESSURE CONTROLLING APPARATUS.

APPLICATION FILED OCT. I2, 1917.

1,358, 1 66. Patented Nov. 9, 1920.

2 SHEETS-SHEET 2.

" f//f f Ill/IIIA UNITED Astares rie-'rar Vorrics.

LINCOLN A. LANG, OF CHICAGO, ELLINS, AKSIGNR TO THE NORTIIERN TRUST` COMPANY, F CHICAGG, LLINIS, A GQRPRATION GF ILLINOIS, (TRUSTEE.)

Speccation of Letters Patent.

Patented Nov. 9, 1920.

Application filed october 12, isla serieu No. 196,115.

To all whom it may concern:

Be it known that I, LINCOLN A. LANG, a citizen of the `United States, residing at Chicago, in the county or' Cook and `State of illinois, have invented certain new and useful lmprovements in Fluid-PressurelControlling Apparatus, of which the Yfollowingis a specication.

My invention relates to improvements in :duid pressure controlling apparatus, and, although capable of various applications, is of particular service when utilized in connection with those devices known among mechanical engineers as servo motor follow-up mechanisms.

ln the usual type of servo motor mechanisms,lthe position of a ponderous member is controlled by a piston in a cylinder to which fluid is supplied by means of some torni oit valve mechanism actuated by a manual-control device, the arrangement being such that a certain movement of the handle will actuate the valves to move the piston a 'like proportionate amount, the piston being so connected to the valve mechanism that at the completion oi such `proportionate movement the valve mechanism is restored to normal condition and the piston brought to rest.` in such mechanisms as heretofore'constructed, the valves for controllingy the flow et duid, both to and from the cylinder, are all actuated mechanically.

ln practice, considerable ditiiculty is eX- perienced in so organizing the valve mechanism and in so timing the speed and degree of opening of the exhaust and the inlet valves as to secure proper operation of the device under dilierent conditions; For instance, in order to secure great sensitiveness and an accurate positioning of the ponderous member in accordance with the movement of the handle or other manually-operated member, it is necessary to secure `a sudden sharp and positive opening of both sets of valves, in-

let and exhaust. On the other hand, it frequently happens that such an adjustment results in a surging or hunting movement of the piston in the cylinder, due to momentum or external forces applied to the ponderous member. These different conditions are directlyr contradictory as to their mechanical requirements, and, so far as l aware, existing types of servo-motori mechanisms have consequently been more or less of a compromise. l

The principal objects o the present invention are to provide in a device of the class described automatic mea-ns tor controlling the opposed forces acting indirectly on the ponderous member, by reason of changes in said forces incident to the actuation of other directly actuated mechanism; to provide an arrangement of the classdescribed which shall beso organized as substantially to elim'- inate paclriiigs and `other force-consuming instrumentalities, thereby improving the mechanical construction in various ways, besides requiring Vmuch lesspovver to actuate the valve mechanism; to provide an arrangement which may be so organized to respond to certain predetermined operating conditionsgto provide zt`actoiy-bi1ilt and adjusted apparatus so designed and constructed by experts as to remove the possibility of improper adjustment by persons in practical charge ot' the mechanism; to providea device ci' the class described which may be made sensitive and positive in its action', while at the same time, hunting, creeping, or other improper movements orl the piston in the cylinder are prevented; to provide a construction of the class described whichshall be simple in design and economical to manufacture; and, in general, to provide an improves and eiiicient apparatus of the character referred to. Y

inthe drawings, which illustrate my invention as applied to the reversing gear of a steam locomotive` Figure l is a side elevation the cylinder and associated apparatus, certain parts being sectionalized the better to illustrate the interior construction;

Fig. 2 is a plan vienT or' the central portion l, V `3 is an enlarged section taken on the #of Fig. 9-

' i isa section tal-ren on the line i-fl Fig. is a section taken on the line 5-5 of Fig. and liig. 6 is asection of a modified form of valve.

Referring to the drawings, l() represents a link or connecting rod which is ,connectedV to a manually-operable member, such as a hand-lever, which can be adgusted in a num- Y the ends of a short shaft 12.

ber of various positions intended to corre.

spond with the particular valve adjustment desired. The valve gear of the locomotive is controlled by means of a pair of connecting links 11, shown best in Fig. n2, keyed to Power to operate the said links 11 by moving the pin 12 is su )lied b ressure fluid, preferabl air i l 7 admitted to a stationary elongated cylinder 13, within which reciprocates an elongated piston 14. The endsof the said cylinder 13 are closed by heads 15 and 1G and the pin 12 is journaled in the center of the elongated piston 14, the ends of said pin projecting through opposite side walls oftheV cylinder 13, slots 17being cut therein for that purpose.

The arrangement so far described is quite similar to the construction set Vforth in my (io-pending application Serial No. 169,217, filed May 17, 1917.V

1n this application, the admission of fluid under pressure to opposite ends of the cylinder 13 is automatically controlled by reason of differences in pressure between the opposite ends of the piston, due to actua-tion of the exhaust valves which control egress of fluid 4from the cylinder. rlhe exhaust vaves are manually operated by the control ro 10. f

4The exhaust valve mechanism is carried by a housing 18 bolted centrallyl to the lower side of. the pistony 14 and projecting Y. downwardly Athrough a slot 19 formed in the bottom wall of the cylinder 13. It should be understood thatf the cylinder 13 and the piston 14 are of sufficient length to allow for a proper length of reciprocatory movement of the piston in the cylinder, in spite of the slots 17 and 19.

The exhaust valves 21 and 22 are of the puppet type and are normally subjected to the pressure of the iiuid in opposite endsof the cylinder Such pressure, added to the pressure of the compression springs 23 and 24, serves effectively Vvto prevent leakage of said valves. ln order to permit convenient assembly of the various valve parts, the cleavage line separating the valve housing 18 from the-piston 1 4 extends through the valve pockets 25 and 23 containing the springs 23 and 24. The upper ends of the valve pockets 25 and 26 are suitably ported, as shown at 25 and 26 to communicate with opposite ends'of the cylinder through-the end cavities of the hollow piston 14. The stems 27 and 28, which are formed as integral parts of the valves 21 and 22, extend loosely through guides 29 and 30 which do not need to. be gas-tight, in view 'of the fact that the openings 31 and 32 exhaust directly into the atmosphere. In the embodiment described herein, the valves are located with their axes vertical and spaced apart along alongitudinal center line Yparallel with the axis of the maincylinder 13. Such location of the valves permits of'then' convenient manipulation by means of a rocklever 33 plvotally mounted on a horizontal shaft mounted in a pair of spaced-apart llugs 35 and 36 formed as integral parts of and fluid will therefore be discharged from the corresponding end ofthe cylinder 113. yExcessive movement of the rocker arm 37 is prevented by a stop-lug 42 formed integrally therewith which plays'betw'een the fixed stops 43 and 44 on one of the lugs.

Fluid under pressureris admitted'to opposite ends of the cylinder through a pair of longitudinally-extending ports 45 and 46 which terminate in valve chambers 47' and 48 located in the bottom portion of a duplex f integral valve-housing 49 bolted to the top wall of the cylinder 13. The valve-chambers 47 vand 48 contain automatic valves 50 and 51 of the puppet type which when closed prevent pressure fluid from passing out of the end of the supply cavity 52. Air

' under pressure is conducted tothe supply cavity through a pipe 53 connected to a convenient source'of compressed air.

lmmediately above the puppet valves 50 and 51 are a pair of solid pistons 54 and 55 arranged to reciprocate in cylindricalaperturesbored in the upwardly-extending portion of the duplex valve-housing 49. In orderto minimize friction, the comparativelyl minute pistons 54 and 55 are not equipped with packing rings, but are simply grooved circumferentially, as shown at 56.' For a purpose which will hereinafter appear, the diameters of the pistons 54 and 55 are slightly greater than the respective diameters of the puppet valves 50 and 51. Immediately above the-upper ends of the pistons 54 and 55 are a pair of what may be termed equalizing chambers 57 and loWer. ends of said conduits terminating, for convenience, in the valve pockets 48 and Said cross-connecting conduits 63 and 64 serve to subject the upper ends of the valve-control pistons 54 and 55 to the pressure of fluid in the correspondingly opposite ends of the cylinder.

In describing the operation of the apparatus, We will first assume that the apparatus is in a deadcondition, with the source of pressure fluid shut off. When the pressure is turned on, fluid which is thus admitted to uthe supply cavity 52 lifts both of the valves 50 and 51 and flows into opposite ends of the cylinder through the ports 45 and 46. Assuming now that the area of each of the pistons 54 and 55 is twenty-five per cent. greater than the area of the corresponding valves 50 and 5l, and assuming` that the supply pressure is one hundred pounds per square inch, it will be evident that as soon as the pressure in one or the other end of the cylinder reaches eighty pounds per square inch, the valve controlling the other end of the cylinder will be automatically closed by reason or' such eighty pounds pressure being communicated to the upper end of the piston controlling such valve through the proper cross-connecting conduit. lli/Te will assume that for some reason, air flows more quickly into the right-hand end o1c the cylinder than into the left-hand end. rlhis Will cause the pressure in the right-hand end to reach eighty pounds per square inch While the pressure in the letthaud end el the cylinder is still inferior. Such eighty pounds pressure being communicated to the equalizing chamber 57 through the cross-connecting conduit 63, will depress the plunger 54 and close the valve 50, preventing further HOW of pres sure fluid into the left-hand end of the cyl inder.

A. condition now exists in which the equilibrium of the piston is destroyed, fortwo reasons: In the Vtlrst place,the pressure in the left-hand end of the cylinder is less than the normal eighty pounds operating pressure; and in the second place, the result oi such pressure in the left-hand end of the cylinder being less than normal is to cause c the plunger' 55 to fail to close the valve 48 and pressure fluid will continue to flow into the right-h and end of the cylinder. When a suflicient difference in pressure has been es .tablished between opposite ends .of the cylluder, the piston will of course commence Vto move toward the left-hand end of the cylinder, and, because of the control rod l() being stationary, the lever 33 Will be rocled on its pivotal axis, thus actuating and opening the exhaust valve 22. Such opening of the exhaust valve 22 causes a sudden drop in pressure in the right-hand end of the cylinder, Which reduces the pressure in vthey equalizing chamber 57 sulii-` ciently to allow the valve 50 to reopen and permit pressure Huid to flowinto the lefthand end of the cylinder until equilibrium is established.

The effect oi' the pressure-equalizing apparatus is considerably increased, by reason of the fact that the piston in moving toward the low-pressure end of the cylinder causes a compression oi"- the fluid therein and a consequent building up of the pressure which increases the pressure on the top of the plunger controlling the valve in the Vhighpressure end of the piston. In addition, the valves 50 and 5l act as check valves to prevent reverse iou' of pressure fluid back into the supply line.

The apparatus functionsin substantially the above described manner Whenever the pistonis subjected toshocks or other eX- ternally applied pressure. l? or instance, assuming that the links 11 are subjected to a pulling stress which tends to move the piston toward the right-hand end of the cyl* inder, movement of the piston toward the right-hand *end of the cylinder at once builds up pressure in the right-hand end of the cylinder, such pressure being communicated to the equalizing cavity 57 and eliecting positive closure of the valve 50. Art the same time, any slight movement of the piston in response tothe pull on the links ll becomes .effective to rock the lever 33 in such. direction as to open the exhaust valve FluidV thereupon rushes out of the left-hand end oli the'cylinder, past the exhaust valve 2l, the resultant drop in pressure being communicated to the cavity 58 and causing the high-pressure fluid in the cavity 52 to raise the valve 5l and enter the right-hand end oi the cylinder to counteract the pullapplied externally to the piston. Hence, any movement of the piston in either direction, due to external forces, Will at once cause a building up of the pressure on one side of the piston to oppose such piston movement, and areduction of pressure on the other side of the piston for a like purpose.

The apparatus is quiclrly and positively responsive to movement of the control rod l0. For example, assuming that the control rod l() is moved toward the right, the effect of such movement is to roel; the lever 33 in a direction to open the exhaust valve 22, whereupon pressure in the yright-hand end or" the cylinder ,villbe relieved, permitting the plunger 54 to rise and admit high-pressure iui'df through the port` 45 into the left-hand end oi the cylinder. The piston thereupon commences to move toward the right-hand end of the cylinder and coni tinues such movement, following up the movement of the control rod l0 until the piston has reached a position which, in view A a small cross-connecting pipe leading from' ofthe final positionv reached'by.V the control rod 10, brings the rock-lever 33 into neutral, with both exhaust valves closed. Y c It will of course be understood that When the control rod is moved to the right, in 'order to eft'ect alike movement of the piston, the exhaust-valve 22 is not required to open to its fullest extent, since even a very slight reduction in the pressure Vin the righthand end of thecylinder will cause the piston to move independently of the increment inpressure in the left-hand end of the cylinder, due to the opening of the inlet valve Y sure end is of course in excess of said mean value. If, when the piston arrives at its desired position, the excess in pressure in the left-hand or high-pressure end of the cylinder is more than sufficient to overcome the friction of the parts, there mayV be in such case a slight opening movement of the valve 27, which Will reduce the pressure in the left-hand end of the cylinder to normal or mean value, thus restoring equilibrium of the apparatus.

f In Fig. 6 I have illustrated a slightly modified form of automatic valve mechanism suitable for independent mounting. In such valve mechanism, the valve proper comprises a ball 65 cooperating with a suitable seatin a unitaryvalve housing 66, one of said valve housings being provided for each end of the cylinder. In order to enable such valve mechanisms to be mounted in convenient locations, Without reference to the position of the main cylinder 13, separate pipesjare employed leading to or from the various parts ofthe valve. 'Io this end,

67 constitutes the main pressure supplyV pipe, 68 is a pipe connecting the valve pocket 69 with one end of the cylinder, and 70 is the other end of the cylinderV to the upper equalizing chamber 71 over the control piston 72. Y Y

For some purposes, it may be of advantage to employ a spring 7 3 above: the upper end of the piston 72, instead of relying on the differencein diameter between the piston 72 and the valve-ball 65. The. use of such spring results in a fixed difference in pressure between the supply and the cylinder, instead of a proportionate difference,

fect of gravity on certain heavy parts, either of the apparatus itself or of the devices which are being moved.' The same remarks apply to a Vcase Where a piston rod is usedV 1n one end of the cylinderV instead of connecting the load to the middle of the piston,

as in the herein-described embodiment.

I'claim: 1 f 1. In a device of the class described, the

combination oi a member acted upon by two opposed forces, positively-actuated mechanism for selectively modifying either of said forces, and means responsive to the change in the modified force for'automatically elfi'ecting a contrary change in the other force.

2.7In adevice of the class describefhthe combination ot a movable member acted upon by tivo opposed forces, positii'fely-actuated mechanism for selectively altering either of said forces and means responsive to the change in the altered force for automatically effecting a contrary change in the other force uponv movement yof said member.

3. In a device of' the class described, the combination of a movable member acted upon by two opposed forces, positively-actuated mechanism for selectively reducing either of said forces and means responsive to the change in the reduced force for automatically preventing a reduction in the other force upon movement of said member.

4. In a device ofV the class described, the combination of a control member, a load member acted upon by opposed, normally equilibrized forces, mechanism for selectively diminishing said forces and mechanism for selectively augmenting said forces, one of said mechanisms being so arranged with respect to said members that independent movement of either of said members Will Y actuate said mechanism to alter one of said directions and acted upon by opposed, nor-` mally equilibrized forces, mechanism for Yselectively diminishing saidforces, and mechanism for selectively augmenting said forces, one of said mechanisms being so arranged with respect to said members that independent movement of either of said members will actuate' said mechanism to 'alter one of said forces, andthe other mechanism being arranged mechanically independent oi' the rst mechanism,` but indirectly actuated thereby automatically by the change in the force altered by the other mechanism.

6. In a device oi the class described, the combination of a load member movable in opposite directions and acted upon by two opposed normally equilibrized forces, a controlling member also movable in opposite directions, diiferentally-actuated mechanism movable into oil-normal condition by independent movement of either of said members, for altering either of said forces and thereby applying power tending 'to move said load member, said power being applied in a direction to normalize said differential mechanism, and means automatically operated by the change in the said altered :torce for preventing a similar change in the other force. Y

7. In a device of the class described, the combination of a load member movable in opposite directions and acted upon by two opposed normally equilibrized forces, a controlling member also movable in opposite directions, diilerentiallyactuated mechanism movable into off-normal condition by independent movement of either of said members, for reducing either oi' said forcesV and thereby applying power tending to move said load member, said power being applied in a direction to normalize said differential mechanism, and means automatically operated by the reduction in the said reduced force for preventing a reduction in the other force. l

8. In a device ot the class described, the combination of a load member movable in opposite directions and acted upon by two opposed normally equilibrized forces, a controlling member also movable in opposite directions, diierentiallyactuated mechanism movable into oit-normal condition by independent movement of either of said members, for reducing either ci said forces andv thereby applying power tending to move said load member, said power being applied in a direction to normalize said dit'- ferential mechanism, and means automatically operated by the reduction in the said reduced :force for eliecting an increase in the other torce and thereby assisting the said power so applied. y

i). In a motor control, in Acombination with theV motor` and its two-way acting powerdelivering member, means for controlling the movements of said power-delivering member, comprising sources of motive power acting oppositely on said power-delivering member and normally holding it balanced and immovable, an independently operable automatic means controlling each supply et motive power, othermeans for unbalancing thepower acting on said power-delivery member to move the latter either way, and cross-connected means betweenthe unbalancing means and said automatic power controls, whereby operation of either unbalancing means to change the power value on one side automatically actuates the power control or the opposite side to bring about cooperation ci' that side supplementing the said unbalancing action. Y, y

l0. In a motor control, in combination with the motor and its two-way acting power-delivering member, means for controlling the movements of said power-delivering member, comprising two independent sources or' motive power acting oppositely on said power-delivering member and normally holding it balanced and immovable, an independently operable automatic means controlling each supply oi2 motive power, direct actuated dil'erential mechanical means igor unbalancing the power acting on said power-delivery member to move the latter either way, and cross-.connected means between the unbalancing means and said automatic power' controls, whereby the operation of either unbalancing means to change the power value on one sidel automatically actuates the power control of the opposite side to bring about cooperation of that side supplementing the said unbalancing action.

1l. In a servo-motor, the combination of a load member movable in opposite directions and oppositely acted upon by two forces exerted by the pressure of two bodies or' fluid, a control member also movable in opposite directions, a pair of alternately operable valves actuated by-differential movement of either of said members with respect to the other, for alternately altering the pressure or' said bodies of iuid and so unbalancing said forces, and valve mechanism automatically controlled by the pressure of said bodies of fluid for maintaining the unbalancing effect due to change in pressure in the body of lluid acted upon by the said valve of the first-mentioned pair of valves byV reversely altering the pressure of the other body of fluid.

l2. In a' servo-motor, the combination of a load member movable in opposite directions and'oppositely acted upon by two forces exerted by the pressure of two independent bodies of fluid, a control member also movable in opposite directions, a pair ot' alternately operable valves mechanically actuated by diierential movement oi either oi' said members with respect to the other, for alternately altering the pressure 'of said bodies of iiuid and so unbalancing said forces, and a pair of valves automatically controlled respectively by the pressure of 'said bodies of liuid for assisting the unbalancing eii'ect dueto change in pressure in the body of'k fluid acted uponiby the Vsaid valve of' the first-mentioned pair of valves by reversely induencing the pressure of the other body of fluid.

13. ln a servo-motor, the combination of a load member movable in opposite directions and oppositely acted upon by two forces exerted by the pressure of tivo independent bodies of duid, a control-member also movable in opposite directions, a pair jof alternately operable valves mechanically actuated by differential movement of either of said members with respect to the other, for alternately reducing` the pressure of said bodies of fluid and so unbalancing said forces, and a pair of valves automatically actuated respectively by reduction of theV equilibrized forces, mechanism for diminishing said forces alternately, mechanically arranged differentially with respect to said members so that independent movement of either of said members rWill actuate said mechanism to reduce one of said forces, and mechanism mechanically independent of the first-mentioned mechanism but actuated automatically thereby indirectly by the reduction in said force for preventing a reduction f in the other force upon movement of said load member.

15. ln-a servo-motor, the combination of double-acting `cylinder means, a piston meniber for said cylinder means, a control meinber movable in opposite directions, a source of fluid pressure for operating` said piston in said cylinder, a pair of' alternately operable valves mechanically actuated by differential movement of either of said members with respect to theother, for alternately reducing the pressure of fluid in respective ends of said cylinder means, and a pair of Valves automatically actuated respectively by reduction of the pressure of fluid in said cylinder ends for-admitting fluid to the end of the cylinder opposite to that in Which the pressure has been reduced.

16. ln a servo-motor, the combination of a .double-acting cylinder means, a piston meinberfor said cylinder means, a control member movable in opposite'directions,

source of fluid pressure forV operating said piston in said cylinder, a pair-of alternately operable valves mechanically actuated by differential movement of either of said members with respect to theV other', for alternately reducing the pressure in respective ends ofsaid cylinder means, a pair of valves for admitting fluid underpressure to' opposite ends ofthe said cylinder means, and

means normally tending to `close said valves. 1T. ln a servo-moton'the combination of double-acting cylinder means, a piston niember for said cylinder means, a control membei' movable in opposite directions, a source of Vfluid pressure for operating said piston in said cylinder, a pair of alternatelyioperable valves mechanically actuated by differential movement of Veither of said niem-v bers with respectfto the other, for alternately reducing the pressure of fluid in respective ends vof said cylinder Vmeans, a pair of' independentlyoperable valves for admitting fluid under pressure to opposite ends oi" the said cylinder'means, and means no1'- mally tending to close said valves.

18. ln a servo-motor, the combination of a double-acting cylinder means, a piston member for saidV cylinder means, a control member movable-in opposite directions, a source of Jluid pressure for operating said piston in said cylinder, a pair of alternately operable valvesV mechanically actuated byV differential movement of either of said members With respect to the other, for alternately reducing the pressure in respective ends of said cylinder means, a pair of valves for admittingfluid under pressure vto 0pposite ends of said cylinder Vmeans, and means normally tendin'gto close said valves, vsaid valves being suitably arrangedto be opened by the pressure of the fluid supply.

19. ln a servo-motor, the combination of double-acting cylinder means, a piston member for said cylinder means, a control meni- Y ber movable in op osite directions a source of fluid pressure for operatingsaid piston in said cylinder, a pair of alternately operable valves mechanically actuated by differential movement of either of said members with respect Vto the other, for alternately reducing the pressure in respective ends of said cylinder means, a pair of valves for adinitting'fluid under pressure to opposite ends ofsaid cylinder means,`and means normally tending toclose said valves and includingv members operated by the pressure of fluidjin the opposite cylinder ends, said valves being suitably arranged to be opened bythe pressure of the fluid supply. v

120. ln a servo-motor, the combination of double-acting cylinder means, a piston member for said cylinder means, a control member movable in opposite directions, ya source of fluid pressure 'for operating said piston in said cylinder, a pair of alternately operable valves mechanically-actuated Vby differential movement of either of said members With respect to the other, for alternately reducing the' pressure in Vrespective ends of said cylinder means, a pair ofV valves for admitting fluid under pressure to oppolil) site ends of said cylinder means, and means normally tending to close said valves and including members operated by the pressure o" fluid in the opposite cylinder ends, said valves being suitably arranged to be opened by the pressure of the fluid supply and the arrangement being such that said valveclosing means is superior to the fluid supply pressure, whereby the pressure in said cylinder means is normally maintained at a less value than the pressure of the fluid supply.

2l. In a device of the class described, the combination of an oscillatable member operated by opposed forces, and control mecha nisin operating independently of said member by the inequality of the opposed forces to regulate the movement of said member.

22. In a device of the class described, the combination of an oscillatable member operable by opposed normally equilibrized forces and control mechanism operable independently of said member by variations in the opposed forces to regulate the movement of said member.

23. In a device of the class described, the combination of an oscillatable member having pressure chambers for applying pressure oppositely to said member, an inlet valve to each chamber and pressure operated means controlling the valve of each chamber by the pressure in the other chamber and oprable by inequality of pressure in the chamers. Y

24. In a device of the class described, the combination of a movable member acted upon by tWo opposing pressures, independent exhaust and inlet valves for controlling the pressure, the former being directly operated and the latter being operated indirectly through the variation in pressure efi-'ected by the operation of the exhaust valve.

LINCOLN A. LANG. 

